Process for forming fibrous mixtures into mats



PROCESS FOR FORMING FIBROUS MIXTURES INTO MATS Filed Feb. 25, 1964 H. BIDWELL Jan. 3, 1967 2 Sheets-Sheet 1 SUPPLY OF AIR DRY STOCK AIR DRY STOCK CONVEYOR STOCK MIXING STOCK RECONDITIONING 6 w m N K G R mm m m e c m 0 S K... Km OT K Y E CI C C TS CE E Y OD ON OI E O V R TN TE TF TC N D 8 SL C S 0 R R B w T C I R A P mmaim zofrdmfiummm xookm ATTORNEY.

Jan. 3, 1967 H. BIDWELL 3,295,342

PROCESS FOR FORMING FIBROUS MIXTURES INTO MATS Filed Feb. 25, 1964 2 Sheets-Sheet 2 INVENTOR.

HOWARD BlDWELL ATTORNEY.

United States Patent 3,296,342 PROCESS FOR FORMING FIBROUS MIXTURES INTO MATS Howard Bidwell, Granby, Mass, assignor of fifty percent to Rachel Bidwell, Granby, Mass. Filed Feb. 25, 1964, Ser. No. 347,314 9 Claims. (Cl. 26487) The present invention relates to new and useful im provements in methods for treating fibers in making composite, consolidated products, such as heavy caliper fibrous mats, compacts, insulating boards and the like, More particularly, it teaches methods for forming papermaking fibers and similar stocks by systems envisioning transforming a continuous, pumpable slurry into a thick fibrous mass having a pastelike and non-free-fiowing consistency, blending such conditioned slurry with proportioned charges of preprocessed, predried, air-dry fibers with a resultant absorption of the existent free liquids in the mixture during a continuous material movement, and reconditioning the blended mixture preliminary to machine forming same into a mat or board or compact or other moulded form and shape, as preferred, absent the Fourdrinier or wet vat or dry vat cylinder mould or other normal instrumentation, commonly identified as wet end accessory apparatus in the papermaking art.

Stated in a broad way, the invention comprehends the blending of a predetermined quota of preprocessed and prepared air-dry material with a predetermined quota of like preprocessed and prepared air-dry material (conceivably taken from the same source of supply), which latter quota is converted via a plurality of fiber preparation machines to a non-flowable wet pulp preliminary to said blending, the former quota and the latter converted wet pulp quota being delivered simultaneously or in superposed relation as to each other in the form of batches of fibers to a stock mixing machine whereat the fibers so delivered are mixed and blended, with the free excess moisture of the material of the quota of wet pulp being absorbed in the course of the blending by the material of the quota of the dry portion in manner such as to allow a fully blended mixture especially suited for extrusion techniques and having a consistency to adapt it for formation into finished forms and shapes as by pressure or other forming procedures incorporating filtration flow effects resulting from created pressure differentials at opposite sides of the mass of the material, as same is being formed.

The invention comprises methods or processes involving relationships and orders of steps, apparatus embodying features of construction and arrangements of parts for the eiiectuating of such steps, and the products of such methods and apparatus which possess characteristics,

properties, and relations of constituents, as exemplified in the detailed disclosure hereinafter set forth and as defined in the below-appended claims.

The techniques herein taught are particularly adaptable in the utilization of low grade materials, norm-ally considered as unusable and therefore classified as waste, into useful products, such as insulation slabs, wall boards, carton an packaging materials, agricultural and horticultural plant-growing media, on a favorable competitive basis as compared with similar products formed from higher quality materials and by more costly production methods.

Without intending to place undue limitations upon the scope of the invention beyond what may be required by the state of the prior art, the particular embodiments hereof may be briefly characterized as embracing the concepts, first, of developing super-strong characteristics in those fibers normally employed in conventional papermaking machines and processes torange quite beyond the ranges attainable with said conventional apparatus and methods, and second, of developing desirable fiber characteristics in relatively inferior and low grade materials in manner such as to bring a wide variety of lowcost materials into a practical, commercially-competitive range, as compared with the higher grade, more-costly materials presently processed by the more-complicated equipment and/or the more-expensive procedures.

More specifically, the invention teaches steps in the forming of reconditioned moist-air dry fibrous mixtures as extruded into continuous ribbon form for formation into sheet, board, block or other forms. It includes the feature of filter-drying the constituent materials by way of induced air and/or gas flowing through the materials under suitable pressure differential conditions imposed upon opposite faces of the mass of fibrous material being formed, which filter-drying is augmented by means for utilizing the waste heat of combustion products as an infiltration medium flowing i-n counterflow directions for accelerating the drying effects and fixing fiber orientation as well as extracting moisture by means of generated centrifugal forces. Such features are so interrelated in new and novel manner to eliminate the need for the usual drying means as in the form of rotating steam heated cylindrical dryers or the like.

The invention teaches the sequential steps of conditioning fibrous material mixtures and filter-drying same to a suitable state for forming same into various types of products, as for example, workable green blank material for press forming into molded shapes as well as sheet, mat, board and other forms.

Low grade non-adhesive materials, such as peat moss and other naturally non-adhesive earth and organic deposits, when wet processed accordingto the teachings hereof, exhibit a development of strong adhesive characteristics of such degree as to allow the formation of rigid, staple, yet-porous, end products advantageously suitable for successfully competing with the more-costly products formed by more-conventional procedures.

According to this invention, the need for wet ends of the conventional Fourdrinier o.r cylinder (wet or dry) types and cooperant drying systems, such as, for example, a plurality of rotary steam heated dryers normal to the forming machine phase of paper and board making, is eliminated. Such offers many attendant advantages in the form of a reduction in operating space, a minimization of maintenance requirements, and a low cost of production, all the while producing novel results hitherto unobtai'nable with such materials.

Another significant feature hereof resides in the fact that higher density stocks, of a type having a limited amount of absorbed moisture and with no free-draining excess moisture, may now be exploited for ready machine processing into various products possessive of improved adhesion and bonding characteristics, so as especially to adapt same for use as building, or packaging or like materials.

As a further refinement of the invention, I provide means for eliminating the necessity of introducing a substantially 99% quota of water to a substantially 1% quota of refined stock for forming purposes, as is so common with conventional papermaking machines, with a consequent eliminating of the requisite Fourdrinier wet end or the wet or dry vat types of cylinder wet ends of conventional papermaking machines. Elimination of the need for such introduction of a high percentage of added water allows the elimination of the related problem of its removal so as not only to simplify the apparatus required but also to reduce operating costs and to nullify a multiplicity of aggravating problems of the papermaker in the forming and drying operations, not to mention to minimize the pollution of natural streams and like Water resources.

Another feature worthy of particular notice is the nowpermitted utilization of vast hitherto wasted quantities of materials, such as bark, sawdust, wood waste, slash and like by-products, each possessive, in varying degrees, of good potential fiber sources.

The characteristic features which I consider to be novel with my invention, as to its organization and operation, will be better understood from a consideration of the following detailed description forming a part of this specification, when read in conjunction with the accompanying drawings in which:

FIG. 1 is a flowline diagram of a stock preparation processing system according to the teachings of the invention;

FIG. 2 is a generally schematic representation of the various components of the apparatus employed in the stock preparation and processing and forming parts of the system of the invention for some types of light specialty end products; and

FIG. 3 is a generally schematic representation of the various components of the apparatus employed in the stock forming part of the system of the invention suitable for heavy caliper types of products such as insulation board and other heavy gage material.

Referring first to FIG. 1, a charge of air-dry stock is transferred from a source of supply thereof via an air-dry stock conveyor to a stock preconditioner, preferentially of a type such as disclosed in my copending patent application, Serial No. 118,756, filed May 17, 1961. The stock so preconditioned is then delivered in seriatim to stock blending and refining means of types such as shown in my copending patent application, Serial No. 315,589, filed October 11, 1963.

Thereafter, the so-blended and so-refined stock is delivered to a wet stock chest for completion of the stock preparation phase preliminary to delivery therefrom to a stock thickener or densifier functioning to remove the free-draining liquid vehicle of the stock and to convert the stock from a dumpable consistency to a non-flowing paste-like physical condition.

The stock thickener or densifier may be any one of several types, such as one comprehending a rotary screen for accelerating the separation of the free-draining liquid vehicle from the fibers by means of gravity, or one comprehending a rotating screen for separating the free water by centrifugal action, or one comprehending a screen press, or equivalent.

The free-draining liquid vehicle, if desired, may be removed from the stock thickener, or densifier and collected by suitable instrumentation of gravity or other type for recirculating-return to the preconditioner for reuse.

The resulting preconditioned stock emanating from the stock thickener or densifier is in the form of an excessmoisture-free, moist, paste-like stock, and is delivered to a stock mixer via a wet stock conveying system operating under automatic or manual control means.

Simultaneously, a predetermined amount of air-dry stock, in an air-dry fiuffed physical state so as to readily mix and disperse with other moist fibers, is also delivered via a conveyor to the stock mixer. Said air-dry stock conceivably will be sourced from the same source of supply, as shown.

The stock mixing operation serves to diversify the mixture by the absorption of moisture through hygroscopic action and capillary attraction, causing the mixture to become a further densified pastelike mass.

Following mixing, the so-conditioned stock is charged into a reconditioner, which will be a modified form of the stock preconditioner described in my copending application, Serial No. 118,756, filed May 17, 1961. The reconditioner kneads and reconditions and also readjusts the moisture content and subsequent pliability of the fibrous pastelike mixture so as best to meet the desired formation characteristics on the machine former. Preferentially the material takes the form of a continuously flowing extruded ribbon of reconditioned fibrous material which is suitable for further forming into final caliper thickness and other dimensions on the former through the use of certain modifications in the reconditioner such as the substimtion of the abrading wheel with an attachment in the form of a flattened inverted funnel acting as a flexible nozzle with the flow entering the non-deformed end and leaving the flattened end, the funnel being adjustable as to width of opening at the discharge to an area of proper relation with the extruding capacity of the reconditioner so as to maintain a sufiicient pressure within the ribbon forming nozzle to prevent channeling.

Thereby a normally pumpable slurry is converted to a non-flowing, non-draining excess-moisture-free stock which is sulficieritly pliable for forming and for permanent fiber fixing and bonding on the machine former to which the stock is delivered in the form of a ribbon of variablycontrolled thickness.

Reference will now be made to FIG. 2 of the drawings.

Charges of air-dry stock 2 are transferred from a source of supply (not shown) via an air-dry stock conveyor 4 to a stock preconditioner 6, from which the preconditioned stock is charged via an outlet 8; into a stock blender 10.

The blended stock is delivered via a conduit 12 in recirculating movement back to preconditioner 6 or via a conduit 14 connecting to conduit 12 and leading to a stock refiner 16. The stock so refined is charged via an outlet 18 to a wet stock chest 20 from which it is delivered via a conduit 22 to a stock thickener or densifier 24.

Any free-draining liquid vehicle is removed from stock thickener 24 through a suitable conduit 26 leading therefrom and is collected as by a save-all 28 or the like. A conduit 30, provided with a meter 31 therealong, directs the free-draining liquid vehicle from save-all 28 back to stock preconditioner 6 for reuse thereat.

The eXcess-moisture-free, moist, paste-like stock is charged from a suitable opening 32 in stock thickener 24 as charges 314 onto a wet stock conveyor 36.

Simultaneously, charges of other air-dry stock and/ or composite mixtures of materials such as asbestos, mica, and other substances including resin powders 44 are delivered to a conveyor 46 for discharge therefrom to a stock mixer 48 concomitantly with the delivery of charges 34 from conveyor 36.

The conveying apparatus employed will be of any known type such as to allow a timed delivery of a quota of charges 34 from conveyor 36 in accordance with the delivery of the other quota of charges 44 from conveyor 46, as the result of which two quotas, each of a predetermined magnitude as to the other, are charged into stock mixing component 48. Each conveyor 36, 46 will incorporate means for automatically stopping one or the other or both deliveries, when and as necessity dictates, to insure the delivery of only proper predetermined quantities of each of the two materials into the common lot of fibers for the blending phase within stock mixing component 4-8.

Following the mixing, the mixed stock is charged via a conduit 50 into a reconditioner 52 from which it is charged in the form of a ribbon of adjustable thickness to a fiber former machine which serves to obviate the need for the Fourdrinier or wet vat and or dry vat wet end devices of conventional paper stock forming machines, and in effect, possesses the characteristics of such other types of machines. It is comprised of: 1, a stockreceiving component or hopper 54 for bringing the stock from reconditioner 52 in a uniform consistency flow across the machine width; 2, a mat-forming component including a peripherally-supported hollow and spokeless shell or cylinder 64, having a foraminous outer surface, being rotatable on a horizontal axis, and having a multiplicity of free moisture extraction boxes 66 disposed therewithin and a multiplicity of air pressure chambers 76 disposed around the outer periphery thereof, and 3, a take-off component to be described.

The stock-receiving component or hopper 54 functions as a stock spreading chamber for distributing the stock before delivery to the forming area on the shell or cylinder 64.

Hopper 54 is mounted adjacent the path of rotation of shell 64 at one side of its vertical axial plane and substantially in a plane with its horizontal axis, on the side thereof where the shell surface is moving upwardly.

The hopper 54 is formed by transversely-spaced vertically-disposed side walls extending rearwardly from opposite ends of the shell 64, the arcuate forming surface of the shell 64 constituting the so-called upper forward wall of the hopper 54, and additionally includes a lower transversely-extending wall which extends outwardly away from its point of contact with the shell 64 to define the unitary bottom and rearward wall of the hopper 54.

Lower edges of the side walls are connected to the respective end edges of the lower and rearward wall on opposite sides of the hopper 54 and their forwardmost end edges terminate adjacent the respective end edge of the shell 64 in manner to extend to and conform to the arcuate peripheral surface of its upper quadrant. Suitable fluid-tight sealing means (not shown) is provided at each such juncture for the suit'able sealing of the respective hopper walls to the shell 64.

The hopper 54 is adapted to receive the reconditioned fibrous paste from reconditioner 52 and to discharge same therefrom through what may be defined as a mouth extending laterally across the machine width adjacent the upper quadrant of the shell 64 with the upper and lower walls of the hopper 54 which define the mouth offering leading edges extending parallel to the shell axis and func- I tioning as slice plates over which the stock flows to the shell surface.

A forming roll 56, of hollow construction without openings, may be disposed within the hopper 54 for rotating counter to the direction of rotation of the shell 64 and may be propelled by a suitable drive mechanism so as to have the same surface speed as the shell 64, all so as to maintain a flow of stock moving in the direction of travel of the shell surface and thereby to keep interference of formation at a minimum.

The mat-forming component comprehends end frames (not shown) positioned at opposite ends of shell 64 for peripherally supporting same for its rotation.

The shell 64 will comprise a hollow, spokeless, cylindrical member disposed in a horizontally-extending manner between the vertically-extending transversely-spaced end frames extending upwardly from a suitable foundation, the shell 64 being peripherally supported at its opposite ends by the respective of the end frames.

Shell 64 is rotatable on its horizontal axis and is covered with a suitably wound or otherwise secured Wire covering over which a suitable wire mesh cloth covering is secured to allow a forming surface comprising a closely perforated or reticulated cylinder with the multiplicity of suction openings therethrough offering a foraminous peripheral surface.

The shell 64 allows a hollow center into which free moisture extraction compartments 66, open to the inner face of the shell 64, may be disposed for ready access and movability. Such compartments 66 may be varied in accordance with various factors, such as variations in the nature of the stock, for better control of the formation of the mat as respects thickness and the like. Each such compartment preferentially, though not obligatorily, includes air and water extraction conduits for the separate withdrawal of air and water therefrom.

Suitable rotating means, such as a worm and quadrant assembly (not shown), will allow rotation of said extraction compartments 66 relative to the shell 64 in order to obtain desired operating positions thereof.

Said extraction compartments 66, alternatively, may comprise a single assembly having a plurality of separatesubcompartments, with the degree of vacuum applied to each being varied, as circumstances may require.

The extraction compartments 66 will be provided with the usual deckle packings for confining the length and width of the respective opening, and pressure differential will be induced by applying vacuum to the compartments 66 according to the length of the drop leg employed with each compartment '66, the depth of each compartment, and the capacity of the pump employed with each compartment.

The function of the extraction means is to attract a desired volume and thickness of the paste-like stock over the exposed shell surface by means of air volume removal rather than bymeans of liquid removal as in conventional applications. It serves to cause the atmospheric pressure in addition to the static pressure to form a heavy fibrous layer over the exposed traveling surface of the shell 64. It also serves to the end that when the stock comes out of the hopper, it is held firmly against the shell to eliminate slough and disturbance of formation.

The resulting mat may consist essentially of individual fibers which are self-interlocked to the extent that they impart good structural and fiexural strength to the resulting dry mass.

A surface smoothing gage roll 68 may be used for an effect similar to the effect of a press roll with the added purpose of providing a uniform smoothed surface to a predetermined gage thickness of fibrous mat on the shell face.

The gage roll 68 may be controllable by suitable adjustable means such as air-loaded cylinders or equivalent means and is disposed adjacent the shell 64, for regulating the thickness of the mat to a predetermined caliper.

Suitably arranged for traveling over the entire width of a portion of the exterior surface of the rotating shell 64 and under gage roll 68 and a hold down roll 72, is an endless compression wire cloth 70 which will travel at the shell perimeter speed. As shown, said wire cloth 70 is adapted to extend over approximately one fourth of the shell circumference. Same serves to compress the mat due to adjustable tension maintained upon the wire cloth 70. Additionally, the wire cloth 70 is returned over a suitable stretch roll 74 for maintaining a pressure against the mat as to maintain its stability at a uniform thickness.

operationally, the damp pliable stock is supplied as a relatively wide, ribbon-thin layer to the mat forming region at the upper ascending quadrant of the shell 64 as by forcing same through the discharge opening and onto the forming surface, with the layer being caused to be drawn to the shell. The stock so applied contains the requisite ratio of fiber and moisture so as to produce the proper fiber pliability for distribution in the formed mat. Sufficient moisture dissipation is effected during the time period that the formed mat remains on the shell 64 to produce a coherent mat capable of being subsequently separated therefrom without deformation. I

Uneven formation is minimized due to the fact, after the 'mat is formed, it is not disturbed by being drawn through a pond or slurry and the induced vacuum is such as to preclude any stock slip back.

The transposition of moisture, induced by a continuing moisture-absorption activity of the dry fibers within the compounded stock mixture so as to withdraw moisture from the intermixed wet processed fibers, gives rise to a stock stiffening condition with the effect of an increased stock density and a seeming decrease in overall moisture content of the compounded stock mixture, thereby offering an impressive adhesive and bonding effect during the forming period such as is unknown in conventional forming practices. The resulting moisture tension effects prevent any separating out of fines or fiber fragments, particles or fibers from any stock mixture having a density of a pliable plastic order, thereby to permit the use of relatively coarse mesh wires, which, in some cases, may be eliminated altogether and a suitably perforated facing sheet substituted therefor.

Suitably arranged so as to be disposed relative to the shell 64 and adjacent the exterior surface of the mat are one or more air pressure chambers 76, each extending over the transverse shell width and each being provided with an adequate connection to a high static blower means (not shown). The first such chamber 76 may be arranged to be superimposed over that part of the traveling compression wire cloth 70 in contact with the mat in between the cooperant hold down rolls 68 and 72.

Within the shell 64 and following the suction boxes 66 are a suitable number of vacuum chambers 78, each disposed radially opposite one of the air pressure chambers throughout the full width thereof and each connected with one or more high volume exhaust fans (not shown) of a capacity for maintaining therewithin a suitable partial vacuum value.

Within the shell 64 and following the vacuum chambers 78, is a high pressure air chamber 80 which extends axiswise through the full width of the inner surface of the shell 64 and adjacent the exterior of the shell 64 at a position radially opposite the high pressure air chamber 80 is a carrying roll 92 mounted for entraining an endless traveling screen cloth apron 84 therearound. Another carrying roll 86 is likewise mounted for entraining the apron 84 therearound. The apron 84 is arranged to travel between pairs of drying ovens or chambers, each constituted by an air pressurized section 94 and an opposed minus pressurized section 96 with the upper run of the apron running through a clearance defined between the opposed sections of each pair.

The air pressured sections 94 are supplied with air from blowers (not shown) and may be equipped with heating pipe coils or other heating means In operation, a furnish may be made up of various wet ingredients and delivered in desired quantity by conveyor 36 to mixer 48 which simultaneously receives from conveyor 46 a proper portion of the preprocessed air dry reprocessed dry stock similar or dissimilar to that stock delivered by conveyor 36, so as to maintain either a batch or continuous flow operation in series with reconditioner 52.

The wet and dry ingredient mixture, upon entering reconditioner 52, may be further adjusted as to density and workability within the reconditioner, as exemplified in my copending application previously mentioned, for suitable application prior to being fed into hopper 54 of the forming means.

By virtue of the hopper arrangement, together with the spreading effect of the forming roll and extraction effect of the extraction boxes and the gaging roll, a predetermined fiber mat thickness may be maintained on the shell.

By virtue of the low moisture-to-fiber ratio content of the fiber mat, high rates of air filtration of the mat are possible as the shell carries the mat between the air pressure chambers and the partial vacuum chambers thereby air-drying the mat by filtration to a self-sustaining fiber bonded condition during the interval of travel time prior to reaching the air pressure mat releasing point where the formed mat is parted from the shell through the aid if necessary, of a suction box 88.

' Heated air may be used, if found necessary in any of the air chambers.

The dry fibrous material supplied by the conveyor need not be machine processed through the machine but can be natural air dried by stock piling after leaving densifier 24, and later reprocessed in apparatus exemplified in my copending application, Ser. No. 172,321, filed February 9, 1962, to the desired fluffed condition.

One great advantage of the above described method of machine processing fibrous substances is the ready adapt- 8 ability to plastic additives either added at mixer 48 or sprayed on the formed mat following 'gage roll 68, or following the parting of the fiber mat from the shell 64 and preceding the air chambers 94 or opera-ted within one of the said air chambers.

Plastics heretofore used on conventional papermaking machines have presented aggravating problems due primarily to their setting and hardening characteristics in the face of the large volume of white water involved and further due to the problems which the :plastics create on Fourdrinier and cylinder wires and other accessories including the pumps, piping and the flow circulating system in general.

In the method hereof, plastics in solution may be applied directly to the formed mat without same contacting the cylinder wire cover. When so applied, the plastic application may permeate the mat without excess and is aided by the filtration air flow through the permeable fiber mass without reaching the cylinder wire cloth or other mechanical parts of the forming machine.

Further advantages in this method of forming fibrous materials is the exploitation of the phenomenon that high density stocks do not foul screen or forming wires as do stocks of conventional consistencies.

For moulded products, the shell may be fitted with mould forms, in which case gage roll 68 may be substituted with a suitably large counter mould roll synchronized with the shell for completing the moulded Shape which would be ejected on passing under the air ejector, or a pair of mould rolls acting in unison for press forming moulded shapes from the mat may be located after ejection by the air ejector.

Where a hard dense board is desired, press rolls may be added, as required following the parting of the mat from the cylinder, or the cut and trimmed sheet may be platen pressed.

A further advantage of the described machine forming is the omission of white water and any excess water vehicle.

Cutting of the finished mat or web can be accomplished by any standard means.

An alternate method of forming a fast drying and curing dense surfaced and reinforced product comprehends inclusion of the application of a low viscous epoxy resin formulation, such as Shell Chemicals Epon or other suitable low viscous amineter-rninated polyamide resin which may be sprayed on the moist mat, sheet or product shape at one point, followed by the separate application of a suitable catalyst at another subsequent point as the traveling mat, sheet or other form passes under a bank of sprays, all so as to exploit the moisture-absorption power of such resin. The application point may be at the shell or at a location after the mat leaves the shell.

Further alternate methods of accelerating the moisture absorption rate of the fibrous mat may include the application of one or more sheets of previously dried similar or dissimilar materials to the moist web under an applied pressure so as to form an integrated finished product which will be more readily handleable due to the rapid moisture absorption by capillary attraction of the applied predried part, either in an one-sided or two-sided application, whereby the resulting dual or triple layer combination as the case may be affords more ready handling by virtue of the moisture distribution caused by the moisture absorption properties of the predried portion of the finished product, preparatory to any further pressing opera tion which may desirably be employed.

For some types of products, the shell or former roll may not be required, in which instance, the fibrous material to be formed may be fed directly from reconditioner 52 to a suitably equipped horizontal traveling screen 184, as shown in FIG. 3. An adjustable variable speed spreading worm type roll is used without a hopper for extending the supply ribbon of stock supplied from reconditioner 52 to the full mat width, followed by an adjustable variable speed gage roll 168 for maintaining proper gage thickness and surface finish to the mat.

A quota of vacuum suction boxes 166 may be maintained with one or more suction chambers 178 as a supplemental accessory. Other suitable moisture extraction means may be otherwise employed, depending on the volume of infiltration air or gas capacity that may be required for a given product being run.

Under some circumstances, radiant gas fired heaters 180, may be arranged under a hood 182 in manner to cause the products of combustion from the gas burners to be drawn through the mat, thereby accelerating both the moisture extraction rate, and also the curing rate of any applied epoxy resin formulation which may be applied between smoothing gage roll 168 and hood 182.

Following the gas fired heaters 180, a supplemental auxiliary section may be employed to further cure the endless mat product, if required. Such is shown in the assembly 190 as consisting of an inverted endless traveling screen 192, the lower side of which holds the mat down in place as the mat glides in a floating manner over a perforated stationary stainless steel drying plate 193 through which the hot gases, the products of combustion from gas fired radiant heaters 194, are drawn through the mat by means of an exhaust blower 196. A hood 198 is employed to allow more uniform curing throughout the mat thickness due to the reverse directional infiltration gas flow, especially desirable in heavy caliper mats.

I claim:

1. In the process for forming reconditioned moist-airdry fibrous mixtures into mat forms comprising the sequential steps, forming a mat by passing a fibrous mixture through a mat-forming component including moving mat forming and carrying surfaces, extracting the free and excess moisture from the applied mat by means of a multiplicity of moisture extraction vacuum boxes disposed adjacent the mat filtrating surface for vacuum adhering the mat to the surface, partially drying the mat by filterdrying means and applying plus pressures at one side of the mat and simultaneously applying minus pressures at the opposite side of the mat while applying a resin and catalyst to one side of the mat.

2. In the process defined in claim 1, in which the step of extracting the free and excess moisture from the mat includes a means of an applied pressure from an endless traveling overlay screen under tension simultaneously applied and in conjunction with moisture extraction boxes, partially drying the mat through filter-drying by applying additional plus pressures to one side of the mat while simultaneously applying fiber reenforcing and bonding resins and resin catalysts while the opposite side of the mat is simultaneously subjected to a minus pressure for accelerating the coating and penetration of the mat by the resin and catalyst.

3. In a process for wet forming reconditioned moistair-dry fibrous mixtures into mat forms comprising the sequential steps, passing a fibrous mixture through a matforming means having moving mat forming and mat supporting surfaces, extracting the free end excess moisture from the moving mat and partially drying the mat while vacuum adhering the mat to the mat supporting surface, applying a plus pressure at one side of the mat and simultaneously applying a minus pressure at the opposite side of the mat while simultaneously applying a resin and catalyst to the mat.

4. In the process as set forth in claim 3, including the step of, applying additional plus pressures to one side of the mat and subjecting the opposite side of the mat to minus pressures while simultaneously applying a fiber reenforcing and bonding resin and resin catalyst for accelerating the coating and penetration of the mat by the resin and catalyst.

5-. In a method for Wet forming reconditioned moistair-dry fibrous mixtures into mat forms comprising, passing a fibrous mixture between moving mat forming and carrying surfaces, extracting the free and excess moisture from the formed mats by mat adhering and moisture extraction vacuum boxes, partially drying the mat forms by filter-drying means, applying plus pressures at one side of the mat and simultaneously applying minus pressures at the opposite side of the mat while applying a moisture absorbing resin and a resin catalyst to the mat.

6. In the process of forming reconditioned moist-airdry fibrous mixtures into mat form within a mat-forming component comprising the sequential steps, forming a mat on a moving vacuum adhering foraminous surface rotating member, extracting the free and excess moisture from the formed mat by means of a plurality of mat adhering and moisture extraction vacuum boxes disposed adjacent a mat filtrating surface, partly drying the mat by .a filter-drying means of applied pneumatic pressure and oppositely-applied vacuum while applying a liquid resin and catalyst to the vacuum adhering mat for coating and impregnating the mat, transferring the resin treated mat while in a yet pliable state by a pneumatic pressure means to an endless travelling carrying screen, and curing the resin treated mat between a plurality of heat curing pneumatic pressure and oppositely-applied vacuum mat filtrating enclosures.

7. In the process as defined in claim 6, including the steps of, smoothing the exterior surface of the mat to a more uniform caliper by means of the compressive effects of an endless screen travelling under tension over a segmental portion of the rotating foraminous surface while vacuum adhering the fibrous mat to a rotating cylindrical foraminous surface.

8. In the process of chemically accelerating the drying of Wet formed mats compositely formed from furnish material mixtures comprising the steps, applying moistureabsorptive-reactive chemical mat reenforcing additives to thickened slurry processed and pre-processed dry fibrous furnish materials, blended and mixed to a paste like consistency, vacuum adhering the paste mixture in mat form upon a moving foraminous surface, extracting the free and excess moisture from the vacuum adhering mat by means of a plurality of vacuum boxes disposed adjacent the mat filtrating surface, and removing the remaining non-chemically absorbed moisture by applied pneumatic pressure and oppositely-applied vacuum.

9. In a chemically accelerated mat drying process as defined in claim 8 including, a mat outer surface smoothing arch tensioned endless travelling screen for stabilizing the outer surface of the vacuum adhering mat furthest removed from the vacuum boxes.

References Cited by the Examiner UNITED STATES PATENTS 1,163,252 12/ 1915 Millspaugh 1622 07 1,718,573 9/ 1922 Millspaugh 162207 2,282,230 5/1942: MacAlpine 264109 2,502,361 3/1950 Zeigler 264-128 2,724,580 11/ 1955 Revallier 2594 2,811,769 11/1957 Craig 264128 2,884,061 4/1959 Lee 162317 2,918,263 12/1959 Eichhorn 259-4 2,995,186 8/ 196 1 De Montigrey 162317 3,088,859 5/1963 Smith 264128 FOREIGN PATENTS 1,069,103 11/ 1952 France.

ROBERT F. WHITE, Primary Examiner. i

F. S. WHISENHUNT, J. R. HALL, Assistant Examiners. 

1. IN THE PROCESS FOR FORMING RECONDITIONED MOIST-AIRDRY FIBROUS MIXTURES INTO MAT FORMS COMPRISING THE SEQUENTIAL STEPS, FORMING A MAT BY PASSING A FIBROUS MIXTURE THROUGH A MAT-FORMING COMPONENT INCLUDING MOVING MAT FORMING AND CARRYING SURFACES, EXTRACTING THE FREE AND EXCESS MOISTURE FROM THE APPLIED MAT BY MEANS OF A MULTIPLICITY OF MOISTURE EXTRACTION VACUUM BOXES DISPOSED ADJACENT THE MAT FILTRATING SURFACE OF VACUUM ADHERING THE MAT TO THE SURFACE, PARTIALLY DRYING THE MAT BY FILTERDRYING MEANS AND APPLYING PLUS PRESSURES AT ONE SIDE OF THE MAT AND SIMULTANEOUSLY APPLYING MINUS PRESSURES AT THE OPPOSITE SIDE OF THE MAT WHILE APPLYING A RESIN AND CATALYST TO ONE SIDE OF THE MAT. 